Arc box



D; ELLIS Aug. 2, 1932.

ARC Box File d Sept. 25, 1927 ,z IE 1: 1 gm INVIENTOR Delbert Ellis ATTO'RNEY Patented Aug. 2, 1932 UNITED STATES PATENT OFFICE DELBERT ELLIS, 0F TURTLE GREEK, PENNSYLVANIA, ASSIGNOR '10 WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A. CORPORATION OF PENNSYLVANIA ARC BOX Application. filed September 23 1927. Serial No. 221,417.

My invention relates to electrical contactors and particularly to arc-extinguishing (leing into the space surrounding the contactor.

A further object of my invention is to provide a unitary structure for extinguishing the arcs incident to the opening of the. contact members of a circuit interrupter that shall be relatively cheap and simple to man ufacture.

Other objects of my invention will become apparent upon reading the following specification taken in connection with the drawing, wherein:

Figure 1 shows a view in elevation from the front side of a contaetor embodying my invention, and

Fig. 2 shows a sectional view taken along the line IIII, in Fig. 1. i i

In circuit interrupters and contactors of the prior art in .which thecircuit is to be opened under load by contacts opening in air, it has been customary to provide a blow-out magnet which would set up a sufficientl powerful magnetic field transverse to tie are which is drawn when the contacts open to deflect it rapidly upward and blow it out.

Such blowout magnets are relatively expensive components of circuit interrupters and it is desirable, in the case of contactors employed for moderate voltages and currents, such for example as for service in induction motor starters, to avoid the necessity for providing such magnets.

In accordance with my invention I employ, instead of the typical blow-out magnet of the prior art, a structure in which the arcs are extinguished within a chamber which has position therein.

then be controlled by said switch.

openings at the top. The upward draft of the hot gases, confined within such a chamber, exerts a force which brings about the rapid extinction of the are. In orderto prevent hot arc gases and molten particles of metal from being projected from the top of this chimney like structure, Iprovide a partition transverse thereto near the top, comprising a metal screen.

\Vhile the arc extinguishing device which I have invented may be used on direct-current circuits, it is particularly effective on alternating current circuits, owing to the fact that when the current passes through zero in the course of the alternating current cycle, the

- ionization of the are path is rapidly destroyed because of the" proximity of the walls of the chamber. The metal screen alsohas a powerful efiect' in destroying ionization. The resistance of the are path is thereby caused to rise to such a value that current flow ceases and the arc remains extinguished.

Referring to the-drawing in detail, a contactor embodying my invention comprises a base panel 1 which may be of any suitable insulating material well known in the art, upon which are mounted stationary contacts 2, with which movable contacts 3 cooperate. The contacts 3 are supported on arms 1 having projections. 5, containing rectangular slots through which the members 3 may be inserted. Springs 6 bear against one end of these slots and retain the members 3- in The lower ends of the members 3 are connected by flexible leads 7 to terminals 8 mounted on the panel 1. The arms 4 are securely fixed to a. cross bar 9, which is supported on trunnions 10, which seat in brackets 11 mounted on the panel 1'.

The contacts 8 are opened and closed by the attraction of a holding magnet 13, which is mounted on the panel 1, and which attracts an armature 14 to which the crossbar 9 is affixed. The magnet may be connected across a phase by connecting one end of its winding to a member 2 and the other end of the winding through a control switch to another contact member 2. The opening and closing of contacts 2 and 3 may The foregoing construction should be clear to ersons familiar with the circuit breaker an the contactor arts.

The line conductors may be connected to terminals 16 which connect directly with stationary contacts '2 and the load conductorsmay be connected to terminals 8 already described. Fig. 1 shows a contactor adapted for asupply circuit having three wires, but it obviously may be readily modified to adapt it for any number of line conductors.v

The arc extinguishing device which is provided in accordance with my invention, comprises a set ofdeionizing chambers 21 rising vertically above each pair of separable contacts. These may readily be constructed by providing a box like structure of suitable refractory insulating material such, for example, as asbestos board having a front Wall 22, a rear wall 23, and two side walls 24. This structure may conveniently be divided into separate chambers for each pair of separable contacts by partitions 25 extending be tween the front wall 22 and rear wall 23. The rear wall 23 is provided with indentations which permit it to slip. over the stationary contacts 2. It may be supported by pushing it down between the contact. 2 and a projecting horn 26 attached thereto.

The upper end of this deionizing structure 7 is provided with a cover 27, which clamps down upon the top of the walls thereof a screen 28 which may, for example, be of copper gauze,'of 16 mesh and comprising wires .03 inches in diameter. The cover member 27 may be held securely in place by bolts 29 which pass through the side walls 24:.

Such being the, preferred structure of a contactor embodying my invention, the operation thereof will be readily apparent.

While I have described one embodiment of my invention, it will be readily apparent to persons of skill in the'art that the principles thereof may be embodied in structures different from that which I have utilized. I therefore desire that the appended claim shall be given the broadest interpretation of which its terms are susceptible in view of the prior art.

I claim as my invention:

A circuit interrupter including a pair of separable contacts mounted within an arcquenching chamber, said chamber being open at the top and bottom and having side walls of refractory insulating material, the walls of said chamber being in two sections and having a wire, screen secured between said two sections across the opening at the top of the chamber.

In testimony whereof, I have hereunto subscribed my name this 19th day of September,

DELBER'I' ELLIS.

When the contacts 2 and 3 open under load,

thearc thereof heats the air within the chambers 21 and causes a rapid upward draft -ing action is extremely rapid and .thearc path so rapidly loses its conductivity that the arc remains extinguished.

Any portion of ionized gas which comes 1n contact with the screen 28 is rapidly deprived of conductivity thereby.

It will, therefore, be evident that I have provided a contactor with means for rapidy extinguishing the are without the necessity of employing a separate blowout magnet. The structure which I have described is simple and may be cheaply constructed out of materials which are standard in the arts. 

